The constant-velocity joint is of a conventional type that comprises two forks forming input and output members of the joint, two spiders, and a central core forming a housing for sliding movement—in a transverse plane—for at least one basically discoidal constraint member that forms the seats for the spherical end heads of the two forks; said constraint member moves about in a transverse plane of symmetry of the central core, to which two surfaces of said housing are parallel. Frequently between each of said two surfaces and the opposing face of said constraint member a laminar ring is interposed, resulting in continuous annular contact with said surface and with said opposing face of the constraint member. This is done in an effort to reduce the loss of lubricating grease, which is mostly there to lubricate between the spherical heads and their seats.